Tube plate for multitubular boilers



March 28, 1939. F. c. HUYGEN TUBE PLATE FOR MULTITUBULAR BOILERS Filed June 20, 1938 Patented Mar. 28, 1939 UNITED STATES PATENT -FFICIEI.vv

Signor to. N-. V. Machinefabriek Bredaf v/h.. Backer & Rueb,.Breda, Netherlands Application-JuneZG; 1938,; Serial No.- 214,819 In the Netherlands January 27, I937" 3 -Claims..

Experience has shown that in a steam boiler with fire tubes of comparatively large diameter leakage often arises at the tube-plate and at the tube ends directly exposed to the flames and that even rupture occurs at the section of the plate between the holes for the fire-tubes. The considerable amount of heat to bewithdrawn from-the flames which continue inthe fire-tubes isapparently not well distributed or not rapidly enough absorbed by the material of the boiler.

The object of the invention is to overcome said difliculty and to this end projections are Welded to the tube-plate at the water side near the holes for the tubes. Said projections may be formed as ridges or lugs and act as cooling ribs so that the tube-plate can transfer its heat more rapidly to the water whereby the average temperature of the tube-plate will more closely approach'that of the much thinner fire tubes. Moreover the projections divide the steam bubbles which are formed in a large quantity near the tube-plate and they further the removal of the rising steam bubbles from the tube plate.

Especially in steam boilers with relatively wide horizontal or inclined fire-tubes having a diameter of about 4 inches and more in which leakage very often occurs the steam bubbles will accumulate under or above each tube and at the tube plate so that they prevent the transfer of heat from the tube-plate. In a steam boiler with horizontal or inclined fire tubes the projections may therefore consist of short baffie plates which are inclined to a horizontal plane and not only act as cooling ribs but also generate unsymmetrical eddy movements around the tubes in order to prevent the steam bubbles from accumulating in the corners between the tubes and the tube-plate. When the steam bubbles are free to rise they set the water in comparatively rapid motion.

A steam bubble which in the centre line at the under side of a tube is prevented from rising has no tendency to move to the left or to the right and grows on whilst also the surrounding water remains relatively quiet. If, however, the symmetrical movement is disturbedor the water set in circulation the steam bubble readily moves away, so that local overheating cannot occur. Inclined lugs welded to the inner side of the tubeplate have a very favourable influence on the movements of the steam bubbles and of the water. If such lugs are welded at the plate sections between the holes for the tubes said sections will be strengthened considerably.

In order to enable the projections to also deflect the steam bubbles from the tube-plate in a boiler welded to the inner side of the tube-plate 2.

having horizontalor substantially horizontalfiretubes the extensions may according tomyinvention consist of baille plates which are inclined to the tube-plate in such a-mannen that their extremities are located at a higher level than their 5 welded-roots;

In a boileroperating with a'small output in which the amount of heat developed 'per cubic foot of the combustion spaceisrelativelysmall the provision-of the projections orlugs makes it 1.0 possible to decrease thehorizontal distance between the vertical rows of tubes so that a substantial square arrangement of the tubes is obtained. Also when the tubes are arranged in staggered relation the space for the steam bubbles between the tubes may under these circumstances be reduced as far as possible, so that the heating surface presented by the tubes may be considerably increased.

When the tube-plate is not uniformly exposed to the heat of the flames the projections may be omitted at the lower heated tubes so that it is not necessary within the scope of my invention to provide a projection at each holefor tubes.

The accompanying drawing illustrates several embodiments of a tube-plate according to the invention.

Fig. 1 is a view of the inner side of a part of a tube plate and Fig. 2 is a section thereof.

Figs. 3 and 4 represent a view of the inner side and a section of a tube-plate of modified form; Figs. 5 and 6 are like views of another embodiment.

The fire-tubes or smoke-tubes l are rolled into the tube-plate 2 and beaded in the usual way. Welded to the tube-plate are studs 3 which transfer heat to the water and consequently cool the parts of the plate between the holes for the tubes. The steam bubbles rising from a lower tube and the water streams generated thereby impact against the studs so that the steam bubbles burst and easily remove from the tube-plate. The water is set in eddy movement and disturbs dead corners in which large steam bubbles could accumulate. An unsymmetrical location of such studs will further the disturbance of the symmetrical movement, whereas with the illustrated symmetrical arrangement the favourable influence of the cooling will possibly exceed the action on the symmetrical movement of the steam bubbles. 7

As shown in Figures 3 and 4 baflle plates 4 are The welding metal 5 is well burnt into the tube-plate and applied at the upper side of the baflle 4 so that the steam bubbles which rise along the under side thereof find a surface which is as smooth as possible. The baflles 4 are perpendicular to the tube-plate 2 and are for each vertical row of tubes inclined in zig-zag relation to each other. The tubes of each vertical row are somewhat staggered relatively to each other, so that in consequence of the guiding action of the bafiies on the steam bubbles free vertical passages for the bubbles are obtained.

Experiments have shown that the bubbles set the water in rapid movement in the narrowest passages between the baflles and the tubes and that dead corners which are formed in the known arrangements at the under side of the tubes are avoided.

In the embodiment shownin Figs. 5 and 6 the tubes l are arranged in staggered relation. The

symmetrical rise of the steam bubbles is disturbed by the bafiles 6 which are inclined to the tube-plate 2 and also to the horizontal plane, so that the steam bubbles are deflected from their vertical path and generate rapid movements of the water around the tubes. The baffles are adapted to deflect the steam bubbles from the tube-plate as the extremity of the bafiie lies at a somewhat higher level than its root.

The baflles 'l of the lowest row are perpendicular to the tube-plate 2 so that they rapidly defleet the bubbles to the side which rise along the tube-plate. The suction action of the water stream generated by the steam bubbles on the water between the baffles 1 and the corresponding tubes l sets said mass of water in motion whereby the steam bubbles which would accumulate at the under side of the fire-tube'when the baffle l was not present are removed.

What I claim is:-

1. A tube-plate for a multitubular boiler having holes for the fire-tubes and projections which are welded to the plate near the tube openings at the side thereof from which the tubes extendeach projection facing part of the circumference of a tube and leaving a free passage between adjacent projections and between the tubes.

2. A tube-plate for a multitubular boiler provided with horizontal or substantially horizontal fire-tubes said plate having projections near the tube openings at the side thereof from which the tubes extend, said projections being formed as bafiies which are inclined to a horizontal plane and each face part of the circumference of a tube so as to leave free passages between adjacent bafiies and between the tubes.

3. A tube-plate for a multitubular boiler provided with horizontal or substantially horizontal fire tubes said plate having projections near the holes for the tubes consisting of baflies which are inclined to a horizontal plane and also inclined to the tube plate in such a manner that their extremities are at a higher level than their roots. 9

FRE'DERIC C. I-IUYGEN. 

